Generate DES key with java card with JCRE 2.1.2

Question

Hi everyone,
I want to generate DES key in my applet . my card supports GP 2.0.1 and JCRE 2.1.2 .
I have tested my applet with JCRE 2.2.1 and used this JCSystem class functions to generate DES key and it compiles and works correctlly .
but when I want to compile my applet with JCRE 2.1.2 I recieve an error which says that API 2.1.2 doesn't support JCSystem class .
so I'll really appreciate it if anyone could tell me how can I generate DES key with JCRE 2.1.2
and also I use JCSystem class functions to get my card's persistent and transistent memory , so with this class not working on JCRE 2.1.2 I have problem to read my free memories too .
So I'll appreciate your help on this matter too.
Best Regards,
Vivian

Answer 1

Hi Vivian,
I don't seem to have any problem with the code you posted. What is the error you are getting? Is it with the compiler or with the CAP file converter? If it is a compiler error, you will need to ensure that the Java Card API jar is in your build path.
Here is a simple class that works with JC 2.1.1 (which will work with JC 2.1.2 as well). I have confirmed that this applet compiles and will return encrypted data to the caller.
package test;
import javacard.framework.APDU;
import javacard.framework.Applet;
import javacard.framework.ISO7816;
import javacard.framework.ISOException;
import javacard.framework.JCSystem;
import javacard.security.DESKey;
import javacard.security.KeyBuilder;
import javacard.security.RandomData;
import javacardx.crypto.Cipher;
* Test JC2.1.1 applet for random DES key.
* @author safarmer - 1.0
* @created 24/11/2009
* @version 1.0 %PRT%
public class TestApplet extends Applet {
    private DESKey key;
    private Cipher cipher;
     * Default constructor that sets up key and cipher.
    public TestApplet() {
        RandomData rand = RandomData.getInstance(RandomData.ALG_SECURE_RANDOM);
        short lenBytes = (short) (KeyBuilder.LENGTH_DES / 8);
        byte[] buffer = JCSystem.makeTransientByteArray(lenBytes, JCSystem.CLEAR_ON_DESELECT);
        key = (DESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_DES, KeyBuilder.LENGTH_DES, false);
        rand.generateData(buffer, (short) 0, lenBytes);
        key.setKey(buffer, (short) 0);
        cipher = Cipher.getInstance(Cipher.ALG_DES_CBC_ISO9797_M1, false);
    public static void install(byte[] bArray, short bOffset, byte bLength) {
        // GP-compliant JavaCard applet registration
        new TestApplet().register(bArray, (short) (bOffset + 1), bArray[bOffset]);
    public void process(APDU apdu) {
        // Good practice: Return 9000 on SELECT
        if (selectingApplet()) {
            return;
        byte[] buf = apdu.getBuffer();
        switch (buf[ISO7816.OFFSET_INS]) {
            case (byte) 0x00:
                cipher.init(key, Cipher.MODE_ENCRYPT);
                short len = cipher.doFinal(buf, ISO7816.OFFSET_CDATA, buf[ISO7816.OFFSET_LC], buf, (short) 0);
                apdu.setOutgoingAndSend((short) 0, len);
                break;
            default:
                // good practice: If you don't know the INStruction, say so:
                ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
}Cheers,
Shane